.center {
    /* left:0;top:0;right:0;bottom:0;
    margin:auto; */
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}
.t-center {
    text-align: center;
}
.left {
    float: left;
}
.right{
    float: right;
}
.cf::after {
    content:'';
    height:0;
    clear: both;
}